US Airliner collides with Military Helicopter in Washington

[14]

MarkwG said:

Starfighter said:

The first statement on the video is that the preliminary report is what happened. The full report will have the likely reasons why that happened. The initial action to close the route is that the separation is not enough

That is why I believe they've missed the point: "separation" has a specific aviation meaning, it's not just a word - It means applying a procedure to ensure the distance between two aircraft is sufficient. The procedure applied here was that the helicopter was required to visually identify the CRJ, & pass behind it. The normal radar separation is likely to be 3 miles, I expect: but once the helicopter has accepted responsibility for separating themselves from the CRJ, the minimum is what they believe to be safe, provided they follow the instructions given - which was to pass behind the CRJ, which, I think, they still believed was landing on 01. The vertical extent of the corridor feels like a red herring, I doubt it was designed for maintaining a vertical distance from aircraft landing on 33: there's no way anyone with any ATC understanding would allow a minima of 75ft.

The equivalent UK rules are:

In the vicinity of aerodromes, the standard separation minima may be reduced if:
(1) adequate separation can be provided by the aerodrome controller when each
aircraft is continuously visible to this controller; or
(2) each aircraft is continuously visible to the pilots of other aircraft concerned and
the pilots report that they can maintain their own separation; or
(3) when one aircraft is following another, the pilot of the succeeding aircraft
reports the other aircraft is in sight and can maintain their own separation.

I expect they were applying (3). The airspace around Washington Reagan is Class B, which the UK doesn't use, however, I don't think that makes a significant difference. There's no specified distance, it's based on the helicopter applying what he/she considers sensible; that's not really a procedure I'd be happy to apply at night, in such crowded airspace, but it is what it is.

They've closed that corridor, which makes sense: I'm just not convinced by their rationale for doing so. I'm interested to see how they have reached their conclusion, hopefully the final report will explain.

The point the NTSB are saying is that visual separation cannot be relied upon, as there has been several instances where aircraft have come close to each other.

[MarkwG]

14 said:

MarkwG said:

Starfighter said:

The first statement on the video is that the preliminary report is what happened. The full report will have the likely reasons why that happened. The initial action to close the route is that the separation is not enough

That is why I believe they've missed the point: "separation" has a specific aviation meaning, it's not just a word - It means applying a procedure to ensure the distance between two aircraft is sufficient. The procedure applied here was that the helicopter was required to visually identify the CRJ, & pass behind it. The normal radar separation is likely to be 3 miles, I expect: but once the helicopter has accepted responsibility for separating themselves from the CRJ, the minimum is what they believe to be safe, provided they follow the instructions given - which was to pass behind the CRJ, which, I think, they still believed was landing on 01. The vertical extent of the corridor feels like a red herring, I doubt it was designed for maintaining a vertical distance from aircraft landing on 33: there's no way anyone with any ATC understanding would allow a minima of 75ft.

The equivalent UK rules are:

In the vicinity of aerodromes, the standard separation minima may be reduced if:
(1) adequate separation can be provided by the aerodrome controller when each
aircraft is continuously visible to this controller; or
(2) each aircraft is continuously visible to the pilots of other aircraft concerned and
the pilots report that they can maintain their own separation; or
(3) when one aircraft is following another, the pilot of the succeeding aircraft
reports the other aircraft is in sight and can maintain their own separation.

I expect they were applying (3). The airspace around Washington Reagan is Class B, which the UK doesn't use, however, I don't think that makes a significant difference. There's no specified distance, it's based on the helicopter applying what he/she considers sensible; that's not really a procedure I'd be happy to apply at night, in such crowded airspace, but it is what it is.

They've closed that corridor, which makes sense: I'm just not convinced by their rationale for doing so. I'm interested to see how they have reached their conclusion, hopefully the final report will explain.

The point the NTSB are saying is that visual separation cannot be relied upon, as there has been several instances where aircraft have come close to each other.

Could you point out where it says that on the video please?

Edited by MarkwG on Thursday 13th March 14:02

[bitchstewie]

[Starfighter]

MarkwG said:

Could you point out where it says that on the video please?

The opening could have minutes quote the near mix figures and it is followed up in the questions at the end.

[MarkwG]

Starfighter said:

MarkwG said:

Could you point out where it says that on the video please?

The opening could have minutes quote the near mix figures and it is followed up in the questions at the end.

I'm sorry, I don't see anywhere where that is mentioned, & I've gone through it a number of times: they're talking about TCAS, not visual separation.

[14]

MarkwG said:

Starfighter said:

MarkwG said:

Could you point out where it says that on the video please?

The opening could have minutes quote the near mix figures and it is followed up in the questions at the end.

I'm sorry, I don't see anywhere where that is mentioned, & I've gone through it a number of times: they're talking about TCAS, not visual separation.

The NTSB didn’t say that visual separation can’t be relied upon, but they did imply it. If aircraft are getting TCAS warnings and having to take avoiding action , then that means that visual separation can’t be relied upon.

[MarkwG]

14 said:

MarkwG said:

Starfighter said:

MarkwG said:

Could you point out where it says that on the video please?

The opening could have minutes quote the near mix figures and it is followed up in the questions at the end.

I'm sorry, I don't see anywhere where that is mentioned, & I've gone through it a number of times: they're talking about TCAS, not visual separation.

The NTSB didn’t say that visual separation can’t be relied upon, but they did imply it. If aircraft are getting TCAS warnings and having to take avoiding action , then that means that visual separation can’t be relied upon.

Not neccesarily: TCAS isn't that refined a tool, even iin its latest version. I can think of a number of examples over the years, where TCAS reacted to a situation that was perfectly safe, all rules properly applied. In this instance, I agree that using visual separation rules was fraught with danger, in this scenario but TCAS would not, indeed did not, help to resolve it.